Internet Protocol
The Internet Protocol (IP) has become the standard for packet-based computer and wireless communications. The IP communication protocol governing data transmission between different networks is referred to as the Internet Protocol (IP) standard. The IP standard has been widely adopted for the transmission of discrete information packets across network boundaries. In fact, the IP standard is the standard protocol governing communications between computers and networks on the Internet. Using the IP standard, computers on different networks communicate with other computers across their network boundaries.
The IP standard identifies the types of services to be provided to users and specifies the mechanisms needed to support these services. The IP standard also specifies the upper and lower system interfaces, defines the services to be provided on these interfaces, and outlines the execution environment for services needed in the system.
A transmission protocol, called the Transmission Control Protocol (TCP), was developed to provide connection-oriented, end-to-end data transmission between packet-switched computer networks. The combination of TCP with IP (TCP/IP) forms a suite of protocols for information packet transmissions between computers on the Internet. The TCP/IP standard has also become a standard protocol for use in all packet switching networks that provide connectivity across network boundaries.
In a typical Internet-based communication scenario, data is transmitted from an originating communication device on a first network across a transmission medium to a destination communication device on a second network. After receipt at the second network, the packet is routed through the network to a destination communication device, and the TCP/IP protocol determines this routing. Because of the standard protocols in Internet communications, the IP protocol on the destination communication device decodes the transmitted information into the original information transmitted by the originating device.
TCP/IP Addressing and Routing
Under the TCP/IP protocols, a computer operating on an IP-based network is assigned a unique physical address called an IP address. The IP address can include: (1) a network ID and number identifying a network, (2) a sub-network ID number identifying a substructure on the network, and (3) a host ID number identifying a particular computer on the sub-network. A header data field in the information packet will include source and destination addresses. The IP addressing scheme imposes a consistent logic addressing scheme reflecting the internal organization of the network or sub-network. Each component node on the IP network can be assigned a unique IP address.
A router is used to regulate the transmission of information packets into and out of the computer network. Routers interpret the logical address contained in information packet headers and direct the information packets to the intended destination. Information packets addressed between computers on the same network do not pass through a router on the boundary of the network, and as such, these information packets will not clutter the transmission lines outside the network. If data is addressed to a computer outside the network, the router on the network boundary forwards the data onto the greater network.
TCP/IP network protocols define how routers determine the transmission path through a network and across network boundaries. Routing decisions are based upon information in the IP header and corresponding entries in a routing table maintained on the router. A routing table contains the information for a router to determine whether to accept an information packet on behalf of a device or pass the information packet onto another router.
The IP-Based Mobility System
The Internet protocols were originally developed with an assumption that Internet users would be connected to a single, fixed network. With the advent of cellular wireless communication systems using mobile communication devices, the movement of Internet users within a network and across network boundaries has become common. Because of this highly mobile Internet usage, the implicit design assumption of the Internet protocols (e.g. a fixed user location) is violated by the mobility of the user.
In an IP-based mobile communication system, the mobile communication device (e.g. cellular phone, pager, computer, etc.) can be called a mobile node or mobile station. Typically, a mobile station maintains connectivity to its home network while operating on a visited network. The mobile station will always be associated with its home network for IP addressing purposes and will have information routed to it by routers located on the home and visited networks. The routers can be referred to by a number of names including Home Agent, Home Mobility Manager, Home Location Register, Foreign Agent, Serving Mobility Manager, Visited Location Register, and Visiting Serving Entity.
IP computer networks also include one or more network elements or components besides routers, such as hubs, switches, bridges, repeaters, gateways, and computer servers. Computer servers provide services to other computers and support the transfer and communication of data over the network. Common servers include authentication, authorization, and accounting activity (AAA) servers, Web servers, mail servers, gateway servers, and Local Area Network (LAN) servers. The various components can also be referred to as nodes.
Cellular and Mobile Communication Technology
A typical cellular communication system is comprised of multiple cell sites, each covering an intended geographic region. Each of the cell sites can be assigned an address for routing information packets, and each of the Mobile Stations can be assigned an address for their physical connectivity to the cell site.
Each cell site supports voice and data communication to the linked Mobile Stations present within that geographic area. A wireless communication link is maintained by a transceiver at or very near the center of the cellular coverage area. The transceiver is coupled to a base station transceiver substation which is coupled to a base station controller that controls the packet transmissions within the cell site area. The base station controller is also coupled to a mobile switching center, which routes calls handled by the base station controller and base transceiver station to a public switched telephone network or a packet data service node interface with the Internet.
Information packets on the communication system are processed by the base station controller for transmission to the public switched telephone network or the Internet. The base station controller processes the information packets for transmission to the public switched telephone network, the Internet, or the Mobile Station. As a Mobile Station moves across cellular boundaries, it changes its connectivity and its connectivity address, which it updates using signaling messages. Routers on the communication network have to be updated with this new connectivity address so that information packet can continue to be properly routed. The address used for routing can be a single IP address, a combination of an IP address and a connectivity address, or some other similar addressing scheme providing packet routing data on the communication network corresponding to the physical connectivity of the Mobile Station.
Telecommunication networks are complex networks used to establish connections between two or more telecommunication devices. Frequently, the devices involved with a telecommunications call or connection are referred to as the originating device and the terminating device. The user typically enters an identifying number into the originating device of the terminating device to which a call is to be placed. The network responds to entry of the identifying number of the terminating device and performs a call setup procedure that establishes, among other things, a connection between the originating device and the terminating device using IP addressing. Call data, voice or multimedia, is then routed between the two devices according the IP addressing assigned to each device.
Voice and data transmitted according to the IP packet standard is the evolving and most current communication protocol for cellular telephone communication. With this migration to the IP standard and miniaturization of computer chip technology, with dramatic increases in clock speeds, computational power, and memory storage, has come increasingly sophisticated services such as email access, streaming video and audio data transfers, instant messaging, text messaging, multimedia applications, picture messaging, Internet website access, e-commerce applications, games, and other services. Cell phones and other mobile stations have accordingly evolved from relatively crude devices limited to telephony communication to near mini-computers with operating features and capabilities equal to if not superior to early personal computers.
Mobile Stations (MS) roam within and across cellular communication sites. Each of the cells possesses one or more transceivers coupled to a Base Transceiver Station (BTS) on the communication network. The BTSs are in turn coupled to a Base Station Controller (BSC). As a MS migrates across cellular borders, its BTS physical connection changes. A MS can be physically located anywhere on the network or sub-network, and its routing address data will change and require updating on other nodes. Wireless IP networks handle the mobile nature of the MS with hand-off procedures designed to update the communication network and sub-network with the location of the MS for packet routing purposes. Because the MS can move within sub-networks and between networks, hand-off procedures are needed to insure that data packets are continually routed to the recipient MS as it moves from one network to another or from one sub-network to another. As the MS roams across the cells, the MS registers its location with the BSC and its home agent with registration messages (e.g. signaling messages, also sometimes referred to as “pings”). Using header extension formats, mobile IP registration messages can be utilized to convey various different data elements accomplishing a variety of tasks.
Cellular and associated communication technology has progressed rapidly. Mobile IP devices have evolved integrating several communication technologies, such as telephony (e.g. voice), messaging, presence, streaming video, and Internet. Global Positioning Satellite (GPS) technology has also been integrated into many mobile IP devices. A present-day mobile communication system is shown in FIG. 1, where the Public Switched Telephone Network (PSTN) 60 is connected to a Mobile Switching Center/Visiting Location Register (MSC/VLR) 40 router. The MSC/VLR 40 is coupled to a Base Station Controller (BSC) 35. The BSC 35 controls the packet transmissions to Base Transceiver Stations (BTS) 20, 25, and 30, which perform communications within the three cell sites 5, 10, and 15.
Communications on the communication system are processed by the BSC 35 for transmission to the PSTN 60, the Internet 70, or the mobile stations (MS) located within each cell site 5, 10, and 15 according to destination address data in the packet header. The MS 65 is coupled to BTS 20 by wireless signal 66. For communications being transmitted to MS 65, the BSC 35 will transmit the communication to the BTS 20. The BTS 25 and 30 are also connected to the BSC 35. Communication from the MSC/VLR 40 flows to the BSC 35 and then to the BTS 20. The BTS 20 transmits communication via a wireless communication link 66 to the MS 65. Reciprocal communications from MS 65 will be processed by the above-identified equipment in the reverse order described above. In this manner, the MS 65 will be coupled to the communication system, the PSTN 60, and the Internet 70 through these connections and system nodes.
The communication system's network core includes a Gateway GPRS Support Node (GGSN) 45 coupled to the MSC/VLR 40 as well as a Serving GPRS Support Node (SGSN) 50. The GGSN 45 is also connected to the Internet 70 and provides communication to and from the Internet 70. The SGSN 50 is also connected to a Home Location Register (HLR) 55, and the HLR 55 is connected in turn to the MSC/VLR 40. The nodes can share the same physical boxes, physically linked and separate, or even linked using routers.
Mobile IP Extensions
Extensions have been defined in the IP protocol, and extensions can be used in similar protocols, to support transmission of variable amounts and types of data in an information packet. This includes address information for mobile nodes, routers, and networks. The extension mechanism in IP permits appropriate addressing and routing information to be carried by any information packet, without restriction to dedicated message types such as discovery, notification, control, registration, and routing data packet formats.
Global Positioning Satellite Technology
Cell phones have incorporated Global Positioning Satellite (GPS) technology in recent years. Two versions for locating a cell phone basically exist. In one, and a relative recent innovation, an actual GPS receiver is incorporated into the phone, which receives signals from orbiting satellites. The GPS phone tracks its location by interpreting the data received from three or more orbiting GPS satellites to compute its longitudinal and latitudinal coordinates. In the second version, the network takes advantage of the constantly broadcast radio signaling messages (e.g. pings) used to passively register a cell phone on a network when roaming to estimate the longitudinal and latitudinal coordinates. Mobile communication companies have been able to estimate the location of a cell phone during an emergency call for several years using triangulation information from the cell towers receiving the signaling signal (i.e. radiolocation). Basically, a module at the cell site base station records the time the caller's signal reached the antenna, and the location of the caller is determined by “triangulating” the caller's distance from several tower receivers. The resulting intersecting distance radiuses from at least three towers provide the location of the cell phone.
Variations and refinements to the triangulation method have been proposed and implemented. Current locator protocols can include angle of arrival (AOA) utilizing at least two towers to locate the cell phone at the point where the reception lines along the transmission angles from each tower intersect. Time difference of arrival (TDOA) where the network determines time difference between signal arrival to compute the resulting distance from three or more towers giving the location. Time Division Multiple Access (TDMA) and Global System for Mobile (GSM) systems, such as AT&T® and T-Mobile®, generally currently use the TDOA method. Location signature is another radiolocation technique that stores and recalls signal characteristics that mobile phone signals are known to exhibit at different locations in each cell to determine location. The more recent introduction of GPS technology into cell phones provides much more accurate geographic location data, but the basic triangulation methods have improved to provide increasingly accurate geographic location data. Hybrid methods exist integrating both GPS and network radiolocation methods, such as Assisted GPS, Advanced Forward Link Trilateration (A-FLT), Timing Advance/Network Measurement Report (TA/NMR), and Enhanced Observed Time Difference (E-OTD). Assisted GPS allows use of GPS reliably indoors (GPS receivers often do not perform reliably indoors) and has been implemented by Verizon® and Sprint®.
These locator protocols have been incorporated for 911 emergency calls or other emergency call systems to allow emergency responders access to accurate location data, as well as other GPS location services. GPS equipped cell phones transmit actual GPS coordinates from the integrated GPS receiver chip. For non-GPS equipped cell phones, an emergency call from a wireless phone triggers an implemented location protocol on the network, such as three modules at three or more nearby cellular antennas to implement a TDOA triangulation location protocol. Under a United States government mandate, enhanced 911 (E911) requires this data to be automatically displayed to emergency center 911 operators with accuracy to within at least 100 meters. More recent developments and implementations have reached resolutions of ˜10 m radius and less. Increasingly, GPS phones are being adopted by major cellular communication providers, and this trend is forecast to continue to include all mobile communication networks and providers. Other countries use similar emergency call numbers and communication protocols (e.g. 999 in the United Kingdom, 112 in the European Union, 000 in Australia, etc). Herein, 911 will be used generically for the differing emergency contact numbers.
Bluetooth® Communication Technology
Bluetooth® is a standard and communications protocol primarily designed for low power consumption, short range (power-class-dependent: 1 meter, 10 meters, 100 meters) communication using low-cost transceiver microchips in each device. Bluetooth enables these devices to communicate with each other when they are in range. The devices use a low-power radio communications system (approximately 1 milliwatt) in the 2.45 GHz frequency, so they do not have to be in line of sight of each other as long as the received transmission is powerful enough. Using a power amplifier on the transmitter, improved receiver sensitivity, and optimized antennas can boost ranges to 1 km.
Bluetooth® has been incorporated in many products, such as phones, printers, modems and headsets. The technology is useful when transferring information between two or more devices that are near each other in low-bandwidth situations. Bluetooth® is commonly used to transfer sound data with cell phones (i.e. with a Bluetooth® headset) or byte data with hand-held computers (e.g. transferring files). Bluetooth® simplifies the discovery and setup of services between devices, and Bluetooth® devices advertise the services they provide much as mobile stations can. This simplifies using services because there is no need to setup network addresses or permissions as in many other networks.
Any Bluetooth® device will transmit the following sets of information on demand:
Device name;
Device class;
List of services; and
Technical information (e.g. device features, manufacturer, Bluetooth® specification, clock offset).
Any Bluetooth® device can perform a discovery inquiry to discover other devices to which to connect, and any device can be configured to respond to such an inquiry. If the device attempting to connect knows the address of the device, it responds to direct connection inquiries and transmits the information shown in the list above as requested. Use of device services can require pairing or acceptance by its owner, but the communication connection itself can be started by any device and maintained until it moves out of range. Some devices can be connected to only one device at a time, and connecting to one device prevents them from connecting to other devices and responding to discovery inquiries until they disconnect from the other device.
Each device is identified by a unique 48-bit Bluetooth® device address (BD_ADDR), identical in nature to an Ethernet address. However, these addresses are generally not shown in inquiries. Instead, friendly Bluetooth® names are used, which can be set by the user. This name appears when another user scans for devices and in lists of paired devices. Most cell phones have the Bluetooth® name set to the manufacturer and model of the phone by default, and up to eight Bluetooth® devices can be connected simultaneously. Bluetooth® systems create a personal-area network (PAN), or piconet, that may fill a room or may encompass no more distance than that between the cell phone on a belt-clip and the headset on your head. Once a piconet is established, the members randomly hop frequencies in unison so they stay in touch with one another and avoid other piconets that may be operating in the same room.
The new E911 system, and other similar systems, still requires a user to physically access a cell phone or other mobile station in an emergency and initiate a regular call by dialing 911. This may be difficult or impossible in certain situations, such as when an elderly person falls and breaks a hip or a woman whose purse, with the mobile station, is out of reach after a vehicle accident or criminal attack. New communication protocols utilizing innovative cellular communication options to make remote 911 calls, or automatic emergency calls, is an advantageous innovation. Also, new innovations, such as using mobile stations as a localized emergency notification system, or a security alert system, offer advantageous emergency contact options.